WASHINGTON (CNN) - Mark Sanford's office is now saying that the South Carolina governor is hiking the Appalachian trail.

In a late Monday e-mail to reporters, Sanford spokesman Joel Sawyer apologized "for taking so long to send this update," explaining that he "was waiting to see if a more definitive idea of what part of the Trail he was on before we did so."

The Appalachian trail stretches from Georgia to Maine.

Sanford has been mysteriously absent for four days, setting the South Carolina political world abuzz with chatter about why he left and where he went. Even his wife Jenny told reporters she didn't know of his location.

State Sen. Jake Knotts, a fellow Republican and opponent of Sanford, told CNN that South Carolina law enforcement officials informed him Saturday that the governor had taken a South Carolina Law Enforcement Division SUV last Thursday and had not yet returned.

"I found out that he was taking frequent trips at odd times of the night in a SLED car with no security," Knotts said. "He would be driving. I got wind that he had taken another one of these types of capers last Thursday, and that nobody knew who he was with."

Knotts said a SLED official told him on Monday that Sanford still had not returned.

Sawyer stressed that Sanford's wife and staff are not concerned about the governor.

"As we said earlier today, it isn't unusual for the governor to be out of pocket for several days after the legislative session," he said. "We knew he would be difficult to reach, and that he would be checking in infrequently. Given the media attention this has generated, we'll obviously update you once we have some more specifics to pass along."

(CNN) - The White House released a statement Monday night from President Obama on the Metro train collision in Washington, DC.

"Michelle and I were saddened by the terrible accident in Northeast Washington D.C. today. Our thoughts and prayers go out to the families and friends affected by this tragedy. I want to thank the brave first responders who arrived immediately to save lives. My staff has been in touch with Mayor Fenty's office and will continue to monitor the situation.

South Carolina Gov. Mark Sanford has mysteriously stepped out of the public eye.

WASHINGTON (CNN) - After a bruising session with the state legislature, South Carolina Gov. Mark Sanford has mysteriously stepped out of the public eye.

Even his wife, Jenny, said Monday that she didn’t know where the governor was, according to the Associated Press. But Sanford's office expressed no concern Monday afternoon about his absence.

Sanford spokesman Joel Sawyer said Sanford “put in a lot of time during this last legislative session, and after the session winds down it's not uncommon for him to go out of pocket for a few days at a time to clear his head.”

However, Sawyer added in a statement sent to CNN: “Obviously, that's going to be somewhat out of the question this time given the attention this particular absence has gotten. Before leaving last week, he let staff know his whereabouts and that he'd be difficult to reach. Should any emergencies arise between the times in which he checks in, our staff would obviously be in contact with other state officials as the situation warrants before making any decisions.”

Earlier in the day, Sawyer said Sanford had simply taken some time away from work to “recharge after the stimulus battle.” Sawyer did not address Jenny Sanford’s comments to the AP in either statement.

State Sen. Jake Knotts, a fellow Republican and opponent of Sanford, told CNN that South Carolina law enforcement officials informed him Saturday that the governor had taken a South Carolina Law Enforcement Division vehicle on Thursday and had not yet returned.

(CNN) - As the aftermath of the Iranian election continues to unfold, a new national survey out Monday shows a slim majority of Americans approve of how President Obama is handling the situation there.

According to a new ABC News/Washington Post poll, 52 percent give the president high marks for his response to the crisis in Iran while 36 percent disapprove. The poll is the first survey to come out in the wake of the country's disputed election just over a week ago.

The president wins stronger marks when it comes to his handling of foreign affairs in general. There, 61 percent approve while 32 percent disapprove.

Top Republicans - including Arizona Sen. John McCain - have criticized Obama for appearing to refrain from direct criticism of the disputed election result and the treatment of protesters over the last week.

Obama has called such attacks 'unjust,' but has also said he does not want to appear as if he is "meddling in Iranian elections."

"The last thing that I want to do is to have the United States be a foil for those forces inside Iran who would love nothing better than to make this an argument about the United States," Obama told CBS in an airing Monday.

White House Press Secretary Robert Gibbs Monday also defended the president's ongoing response to the situation in Iran.

"The president continued to watch the situation evolve in Iran and speak out forcefully on behalf of justice and to warn the government against the use of violence," Gibbs said.

Obama is also expected to address the situation at a press conference Tuesday.

The poll, conducted from June 18-21, surveyed 1,001 adult Americans and carries a margin of error of plus or minus 3.5 percentage points.

WASHINGTON (CNN) - West Virginia Sen. Robert Byrd's hospital stay will likely extend for at least another week, his office said Monday.

Byrd, a 91-year-old Democrat, entered the hospital on May 15 as a precautionary measure. A statement by his office three days later said he was
expected to be released "in a few days."

However, Byrd developed a staph infection while hospitalized, and his office said Monday he "continues to improve but remains in the hospital while he undergoes physical therapy and treatment for" the staph infection.

Byrd, a Democrat, "is not expected" to be in his office this week, according to the statement. It said Sen. Patty Murray, D-Washington, will help fill in for Byrd by managing the chamber's consideration of the Homeland Security Appropriations bill for fiscal year 2010 this week.

"Sen. Byrd is resuming some of his official duties while recuperating, including signing several ... bills as president pro tempore of the Senate, and
working with staff on upcoming appropriations bills," the statement said.

Byrd was first elected to the U.S. Senate in 1958, and is the chamber's longest-serving member.

Secretary of State Hillary Clinton canceled a planned trip to Greece and Italy this week because she is still recovering from surgery to repair her fractured elbow.

WASHINGTON (CNN) – Secretary of State Hillary Clinton canceled a planned trip to Greece and Italy this week because she is still recovering from surgery to repair her fractured elbow.

In Trieste, Italy, Clinton planned to attend meetings with her Group of Eight counterparts on Iran, the Middle East peace process and the War in Afghanistan. She also planned to take part in a gathering of the Organization for Security and Cooperation in Europe in Corfu, Greece, which was expected to focus on the tensions between Russia and Georgia.

The announcement was first made by Deputy Secretary of States James Steinberg, who said he would represent the United States at the meeting in Greece, while Undersecretary of State William Burns will attend the meetings in Italy.

Clinton, who fell in the State Department garage last week, had surgery on Friday. Spokesman Ian Kelly said she was at the State Department Monday, where she made calls to the Greek and Italian foreign ministers to express her regret at having to cancel the trip.

Negotiations between Democrats and Republicans over health care reform have stalled.

Washington (CNN) - Negotiations between key Democrats and Republicans in the Senate over health insurance co-ops as an alternative to a government-run health plan were at an impasse Monday over how much federal government involvement there should be in the creation and running of the co-ops, according to senators and aides involved in the talks.

The negotiations could hold the key to bipartisan compromise.

Most Democrats want a heavy federal presence to ensure the co-ops can adequately compete with the big insurers and help drive down costs, but Republicans say they will back co-ops only if the touch from Washington is very light. Republicans say anything more that that is akin to the government-run proposal they uniformly reject.

"It's clear they are not talking about anything close to a national plan with enough clout to keep the insurance companies honest," said Sen. Chuck Schumer, D-NY.

Schumer, an influential member of the Democratic leadership, has been working behind the scenes on a co-op plan that Democrats can live with.

WHITE HOUSE (CNN) - It's a smaller stage than they're use to standing on but the band Styx stopped by the White House briefing room Monday and posed for pictures behind the podium as well as with reporters who are fans of the group.

A small crowd of journo-groupies trailed the group as they had a look at the briefing room and other press work spaces while meeting with reporters, producers, and photojournalists.

The band, with hits including Mr. Roboto and Come Sail Away, is in town for a show in the DC area but stopped by the White House Monday to get a quick tour.

(CNN) - Los Angeles Mayor Antonio Villaraigosa says he will not run for governor of California next year.

Villaraigosa made the announcement in an exclusive interview on CNN's The Situation Room with Wolf Blitzer.

The mayor, who was re-elected earlier this year, told Blitzer "the answer's no. I make that decision, as I've said many times, because I love the city I was born and raised in."

"I can't leave this city in the middle of a crisis, it's as simple as that," added Villaraigosa. "I was elected mayor and re-elected by the people of this city. They've given me the honor of a second term and I feel compelled to complete the promise that I've made to them."

"For several weeks now, Mayor Villaraigosa has been telling donors he doesn't have the fire in his belly to run for Governor," said CNN National Political Correspondent Jessica Yellin. "The timing was awful for him – he's just been re-elected mayor. And he's under a lot of pressure to make good on some of his promises to turn around Los Angeles."

San Francisco Mayor Gavin Newsom announced in April that he would run for Democratic nomination for governor in next year's election. California Attorney General and former governor Jerry Brown indictes he plans to run as well, but he has not officially tossed his hat into the gubernatorial ring. Lt. Gov. John Garamendi may also join the contest.